The invention relates to a dirt-collecting device for a floor-cleaning machine, for picking up a liquid from a floor surface which is to be cleaned, having a carrier and at least one wiping member for wiping the floor surface, the carrier and the at least one wiping member forming boundaries of a suction channel which opens out into a suction mouth and of which the free cross-sectional area, through which a suction stream can pass, decreases, at least in one channel portion, in a direction away from the suction mouth.
The invention also relates to a floor-cleaning machine comprising at least one dirt-collecting device.
Floor-cleaning machines typically comprise a cleaning device with cleaning elements such as, for example, rotating brush rollers or plate brushes, which can be used to detach dirt from the floor surface which is to be cleaned. The operation of detaching dirt is assisted by the floor surface being subjected to the action of a cleaning liquid, for example water. By means of the dirt-collecting device mentioned in the introduction, the dirty liquid, i.e. the mixture of the cleaning liquid and the detached dirt, so-called dirt liquor, can be picked up from the floor surface by being sucked up. For this purpose, the floor-cleaning machine has a suction unit which is connected to the dirt-collecting device, so that it is possible to generate, within the suction channel, a suction stream, under the action of which the dirty liquid can be transferred from the suction channel, via the suction mouth and a suction line connecting with the suction mouth, into a dirty-liquid tank of the floor-cleaning machine. The at least one wiping member and the carrier form boundaries of the suction channel. For the purpose of delimiting the suction channel, it is additionally possible to use at least one boundary wall which preferably has a flexible configuration and need not necessarily come into contact with the floor surface.
In the case where the suction channel of the dirt-collecting device has a constant cross-sectional area over its entire length, the speed of the suction stream flowing through the suction channel decreases as the distance from the suction mouth increases. This makes it more and more difficult for liquid to be picked up as the distance from the suction mouth increases. In order, nevertheless, to achieve the situation where the liquid which is to be picked up can be picked up effectively over the entire length of the suction channel, U.S. Pat. No. 3,065,490 proposes a dirt-collecting device in which the free cross-sectional area of the suction channel, through which the suction stream can pass, decreases in a direction away from the suction mouth. The decrease in the free cross-sectional area results in an increase in the speed of the suction stream, so that the liquid can be sucked up effectively over the entire length of the suction stream.
In the case of the dirt-collecting device according to U.S. Pat. No. 3,065,490, the free cross-sectional area of the suction channel is decreased in that the portion of the carrier which bounds the suction channel is curved in a complicated manner along the suction channel. This requires costly production of the carrier by means of a complex production method.
It is an object of the present invention to provide a dirt-collecting device of the type in question and a floor-cleaning machine of the type in question which can both be produced in a more cost-effective manner.